In what movie/book/TV show was a character internally tormented by the fact that he was indirectely responsible for his brother being killed by a zoo animal?

This has been bothering me and a few other people for weeks. Everyone remembers this scene/chapter, but no one can remember the rest of the story or where it came from. We’ve tried googling the shit out of it to no avail. Anyway, we’re pretty sure the movie/book/show was largely a comedy, and there was some random point at the end during which the protagonist recalls (in a humorous way) the time that he was at the zoo with his brother, and his brother fell into the gorilla/tiger/bear/monkey/hyena cage and died. What was this? Please help.